The IP (Internet Protocol) defines the format for the addresses and packets used within the Internet. An IP address is easily readable by an IP network; however, it is difficult for most humans to remember. A symbolic name called a domain name, such as “uspto.gov”, is easier to remember and is more meaningful to a human. The domain name has a corresponding IP address that can be retrieved from a DNS (Domain Name Service). Domain name resolution is the process of converting the domain name to an IP address.
The number of domain names is too large to maintain on a single computer and is therefore distributed amongst computers known as DNS servers. Since the database is distributed, a DNS server may not have the information required to resolve the IP address. Thus another server may need to be polled. In some cases the DNS server does not even respond to the request, for example, if the DNS server was not operational. For a data processing system that polls the DNS servers sequentially, sometimes the domain name resolution is not resolved by the first request DNS server polled. This may slow down the domain name resolution process. This slow down is particularly noticeable when multiple sessions, such as multiple WAN interfaces, are active on the data procession system. This is because there are potentially more domain name servers to send the domain name resolution request and increases the possibility that the first DNS server polled cannot resolve the request.